Drilling fluids generally contain certain additives. For example, such additives can be a viscosifier, a suspending agent, a dispersant, a thinner, an anti-balling additive, a lubricant, a wetting agent, a seepage control additive, a drilling enhancer, a penetration rate enhancer, a corrosion inhibitor, an acid, a base, a gelling agent and buffers.
Drilling fluids can be used in both oilfield applications and also in other industrial settings. During the drilling of oil and/or gas wells, a drill bit at the end of a rotating drill string, or at the end of a drill motor, is used to penetrate through geologic formations. During this operation, drilling mud is typically circulated through the drill string, out of the bit, and returned to the surface via the annular space between the drill pipe and the formation. Drilling mud serves numerous functions, including cooling and lubricating the drill string and drill bit, counterbalancing the pressures encountered in the formation using hydrostatic pressure, providing a washing action to remove the formation cuttings from the wellbore, and forming a friction reducing wall cake between the drill string and the wellbore.
Drilling fluids for sinking wells in rock and bringing up the rock cuttings are flowable systems which may be assigned to any of the following three classes: purely aqueous drilling fluids, oil-based drilling fluids, which are generally used as so-called invert emulsion fluids, in which the aqueous phase is heterogeneously distributed as a fine dispersion in the continuous oil phase. The third class of known drilling fluids is built up on water-based o/w emulsions, i.e. on liquid systems which contain a heterogeneous, finely disperse oil phase in a continuous aqueous phase.
In addition to the basic constituents of a drilling fluid such as the lubricant itself such systems may as mentioned above also contain a number of additives, depending on the specific type of application.
Unfortunately, many of such additives are sensitive to the heating that occurs during drilling and will therefore only have a limited life time when in use.
Accordingly, in particular for demanding applications a continuing need exists for drilling fluids in particular in the fields of oil and gas drilling applications that are effective as rheology modifier, viscosifier, lubricant and/or emulsifier additives that are resistant against high temperature degradation or decomposition.